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Post subject: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 9:55 am
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Just for sharing:
Trying to tame the ice pick in a HRD II (Made in Mexico) I´ve found that rolling the guitar volume pot off always, something like 9 or 8.5 (from 1 to 10), and compensating it raising the amp volume a little bit, helps to reduce the ice pick highs. Simple but effective! Hope it helps somebody...

My settings (always on clean channel (input 1) and Bright switch on):

- Volume (from 1 to 12): 4 (for low output pickups: single coils), 3 (for medium output pickups: P90, vintage humbuckers)
- Treble: 4 (for bright guitars), 6 (for dark guitars)
- Mids: 5 (for bright guitars), 6 (for dark guitars)
- Bass: 5 (for bright guitars), 6 (for dark guitars)
- Presence: 4 (for bright guitars), 6 (for dark guitars)
- Reverb: always 2

Speaker: Jensen ALNICO


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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 10:00 am
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Turning the Bright Switch OFF would help even more to tame the ice pick highs. :wink:

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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 10:08 am
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If the bias has never been adjusted, doing so can improve the sound. These amps come from the factory with a bias setting that is considered by most to be quite cold.

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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 10:53 am
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bluesky636 wrote:
Turning the Bright Switch OFF would help even more to tame the ice pick highs. :wink:


Yeah, it heps :) but I prefer the tone with the bright switch on and the presence knob down. :D


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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 10:55 am
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shimmilou wrote:
If the bias has never been adjusted, doing so can improve the sound. These amps come from the factory with a bias setting that is considered by most to be quite cold.

You are right! ;) Mine is biased at 68mA, wich is on the hot side.


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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 12:46 pm
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fenderela wrote:
shimmilou wrote:
If the bias has never been adjusted, doing so can improve the sound. These amps come from the factory with a bias setting that is considered by most to be quite cold.

You are right! ;) Mine is biased at 68mA, wich is on the hot side.


I doubt that. If true, your tubes would be burnt to a crisp (about 100% max plate dissipation). If you are measureing using the Fender test point, you divide that number by 2 for 34 mA per tube. That's pretty cold.

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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 12:47 pm
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fenderela wrote:
bluesky636 wrote:
Turning the Bright Switch OFF would help even more to tame the ice pick highs. :wink:


Yeah, it heps :) but I prefer the tone with the bright switch on and the presence knob down. :D


Suit yourself.

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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 1:22 pm
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bluesky636 wrote:
fenderela wrote:
shimmilou wrote:
If the bias has never been adjusted, doing so can improve the sound. These amps come from the factory with a bias setting that is considered by most to be quite cold.

You are right! ;) Mine is biased at 68mA, wich is on the hot side.


I doubt that. If true, your tubes would be burnt to a crisp (about 100% max plate dissipation). If you are measureing using the Fender test point, you divide that number by 2 for 34 mA per tube. That's pretty cold.


Sorry, I wanted to say 68 mV


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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 3:08 pm
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When I refer to a "hot" or "cold" bias, I am referring to the current/temperature of the output tubes, and I believe that most people understand it this way also. A good range for this amp, with 6L6 30-watt tubes, is between 70 mV and 100 mV, colder for longer tube life, hotter for earlier breakup. Adjust according to tube wattage rating of the tubes that you have. The 5881 tubes appear to be about 25-watt, in which case 68 mV isn't too bad. Some tubes won't go much higher than about 70 mV or so, and it's OK if your tubes won't go much higher than that, some are just lower current draw than others. This is based on a Plate voltage of approx 430 VDC for the HRDlx.

Thanks for sharing your settings. Many people like suggestions like yours. :)

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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 3:38 pm
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fenderela wrote:
bluesky636 wrote:
fenderela wrote:
You are right! ;) Mine is biased at 68mA, wich is on the hot side.


I doubt that. If true, your tubes would be burnt to a crisp (about 100% max plate dissipation). If you are measureing using the Fender test point, you divide that number by 2 for 34 mA per tube. That's pretty cold.


Sorry, I wanted to say 68 mV


That is still 34 mA cathode current per tube, which is fairly cold.

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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 4:11 pm
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fenderela, like Bluesky & Shimmy stated 34mA per 6L6GC (~14.5 watts of idle bias per tube at 430VDC) is too cold idle bias. Too cold bias = sterile, abrasive ("ice-pick") tone. If you do not want to adjust the idle, I'd have a good tech do it.

For a quality grade 6L6GC, ~18-20 watts of idle dissipation per 6L6GC (which is 42-46mA per tube -- or a measured 42 - 46mV with a Bias Tool) is a good starting point. Once the amp's idle bias is set to the proper range for a 6L6GC, the amp's tone will become warmer with smooth overtones. And that "ice-pick" at volume with become less of an issue.


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Post subject: Re: Taming the ice pick in a HRD
Posted: Tue Jul 31, 2012 11:36 pm
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BMW2002Ti wrote:
fenderela, like Bluesky & Shimmy stated 34mA per 6L6GC (~14.5 watts of idle bias per tube at 430VDC) is too cold idle bias. Too cold bias = sterile, abrasive ("ice-pick") tone. If you do not want to adjust the idle, I'd have a good tech do it.

For a quality grade 6L6GC, ~18-20 watts of idle dissipation per 6L6GC (which is 42-46mA per tube -- or a measured 42 - 46mV with a Bias Tool) is a good starting point. Once the amp's idle bias is set to the proper range for a 6L6GC, the amp's tone will become warmer with smooth overtones. And that "ice-pick" at volume with become less of an issue.


I didn´t adjust the bias. My tech did it, and he told me:

With 6L6GC - 30W:
.......Hot (70%) Avg (60%) Cool (50%)
300V 70mA 60mA 50mA
325V 65mA 55mA 46mA

Thanks!


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Post subject: Re: Taming the ice pick in a HRD
Posted: Wed Aug 01, 2012 7:52 am
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Either you misunderstood, or gave the wrong numbers, or your tech's math skills are seriously lacking. :o Also, if you have only 300-325 VDC on the output tubes' Plates, something is very wrong with your amp. You should have closer to 430 VDC on the Plates in a HRDlx. The HRDvl is closer to 485 volts on the Plates. The BJr has a Plate voltage closer to 330 VDC, but of course uses EL84 output tubes.

Consider that the test point reading at the output tubes' Cathodes in mV, which can be directly translated to mA since the reading is across a 1-ohm resistor, is for two tubes. The Cathode current for one tube will be half of the test point reading. To calculate the wattage dissipated at idle, use the following simple formula, and numbers are for one tube. Plate voltage times Plate current equals Plate wattage. Typical idle wattage for most amps will be between 50% and 70% of the tubes max Plate wattage dissipation rating. For the purposes of this discussion, Cathode current can be used in lieu of Plate current as it is "close enough". So, 70 mV (70 mA) at the test point equals approximately 35 mA of Cathode current per output tube, or .035 A.

Using the numbers that you provided, 300 x .035 = 10.5 watts per tube, which is beyond cold, it's freezing at approximately 33%, and would result in very sterile, harsh or "ice-picky" tone. 325 x .032 = 10.4 watts per tube, same as above.

Using numbers that would normally be found in a HRDlx, 430 x .035 = 15.5 watts per tube, which is about 50% and is at the lower end of the range, on the cool side but still acceptable. Raising the current can provide a warmer fuller tone, but too much can result in shorter tube life.

In any case, 68 mV at the test point of a HRDlx is not hot by any reasonable measure, and I hope that you just misquoted the numbers for the Plate voltage, otherwise something is very wrong with your amp, or something is wrong with the tech.

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Post subject: Re: Taming the ice pick in a HRD
Posted: Wed Aug 01, 2012 7:57 am
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+1

Time to find a competent tech.

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Post subject: Re: Taming the ice pick in a HRD
Posted: Wed Aug 01, 2012 8:29 am
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shimmilou wrote:
Either you misunderstood, or gave the wrong numbers, or your tech's math skills are seriously lacking. :o Also, if you have only 300-325 VDC on the output tubes' Plates, something is very wrong with your amp. You should have closer to 430 VDC on the Plates in a HRDlx. The HRDvl is closer to 485 volts on the Plates. The BJr has a Plate voltage closer to 330 VDC, but of course uses EL84 output tubes.

Consider that the test point reading at the output tubes' Cathodes in mV, which can be directly translated to mA since the reading is across a 1-ohm resistor, is for two tubes. The Cathode current for one tube will be half of the test point reading. To calculate the wattage dissipated at idle, use the following simple formula, and numbers are for one tube. Plate voltage times Plate current equals Plate wattage. Typical idle wattage for most amps will be between 50% and 70% of the tubes max Plate wattage dissipation rating. For the purposes of this discussion, Cathode current can be used in lieu of Plate current as it is "close enough". So, 70 mV (70 mA) at the test point equals approximately 35 mA of Cathode current per output tube, or .035 A.

Using the numbers that you provided, 300 x .035 = 10.5 watts per tube, which is beyond cold, it's freezing at approximately 33%, and would result in very sterile, harsh or "ice-picky" tone. 325 x .032 = 10.4 watts per tube, same as above.

Using numbers that would normally be found in a HRDlx, 430 x .035 = 15.5 watts per tube, which is about 50% and is at the lower end of the range, on the cool side but still acceptable. Raising the current can provide a warmer fuller tone, but too much can result in shorter tube life.

In any case, 68 mV at the test point of a HRDlx is not hot by any reasonable measure, and I hope that you just misquoted the numbers for the Plate voltage, otherwise something is very wrong with your amp, or something is wrong with the tech.


Thanks shimmilou. I don´t know... Maybe he wanted to say 68mA per tube (so 136mA at the test point)??? So 325 x 0.068 = 22,1 watts per tube??? Does it has any sense?

By the way, mine is an European HRDII, if it has sth. to be with the plate voltage...


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